Hard disks are an integral component of current personal computers (PCs). Current PC architectures rely on an extremely tight integration and physical co-location of the primary system hard disk with the other PC components in order to function properly. This underlying architectural requirement of PCs is a source of multitudinous problems, inefficiencies and limitations. For example, the architecture forces users to store and administer all important user “state” (documents, files, settings, certificates, and so on) locally on the hard drive in a user's desktop PC.
The architecture causes information technology (IT) organizations to incur large costs to support and manage the infrastructure of stand-alone PCs and networked PCs. Additionally, corporate IT organizations lose control of corporate assets stored on individual hard drives. For example, backup and restore programs for the desktop are ineffective and difficult to administer. Any problem that involves a non-booting hard drive requires either a service call and/or physical access to the PC. Corporate assets are frequently lost due to desktop storage that is not professionally managed. IT organizations also find it difficult to “police” non-approved uses of PCs because they cannot manage the user state directly.
The tight integration and physical co-location of the primary system hard disk with the other PC components results in a lost opportunity for pooling of storage from users in a corporation. Today's corporate users require an average of about 5 GB of disk space. The smallest hard drive available on a PC today is about 30 GB (which is expected to increase in the future to 40 GB, 60 GB, and 80 GB with Moore's law). As a result, the amount of wasted space in today's average corporate PC exceeds 80% and is growing.
Storage management has advanced tremendously in the last 5 to 10 years. The ability to virtualize LUNs (logical disk units) and seamlessly manage storage “behind” these virtualized resources has driven significant cost savings into the administration of corporate storage. None of these advances can be leveraged for storage that is located on users' desktops.
This tight integration and reliance of PCs on the internal hard drive has other ramifications for the user's experience. Hard drives take time to spin up. This is a significant part of the time required to boot a PC or to resume from hibernation. Hard drives are one of the few components inside a PC that have moving parts. As a result, they are one of the least reliable components of a PC and they represent one of the largest contributors to heat and noise for the PC.
To solve these problems, the PC industry has attempted many times to remove the hard disk from corporate PCs. Many of these attempts of creating a disk-less “net” PC rely on technologies such as BOOT-P and PXE (Preboot Execution Environment) to boot and run from centralized storage. None of these attempts has been successful. One reason that these attempts have not been successful is that Ethernet and TCP/IP cannot guarantee the consistent and low latency ‘block’ access that the PC architecture and operating system demand in order to operate reliably. Another reason is that critical files such as the page file and the system registry files must be local to the PC to provide the user with a reliable experience. Additionally, most PC applications such as email, file sharing, and Web access require an operating network to run properly. A user's productivity is negatively impacted when the network is operating unreliably or at less than optimal levels. For example, typical outages on today's networks can last for periods of up to five to six seconds. Data can be lost if an operating system is performing page operations when an outage occurs.